For windows users, the best free option seems to be the DIYPhotobits Camera Control, which is currently at Version 4.0. A basic bracketing function has been added. This should help high dynamic range (HDR) shooters especially who are shooting with Nikon DSLRs such as D40, D40X, and D60 that do not have built-in automatic bracketing function. You could manually change exposure settings, but avoiding camera movement may be difficult even with camera mounted on a tripod.